With the goal to effectively produce a cadre of trained and ready foreign language (FL) teachers, the academic debate is not only focused on what content knowledge and skills the teacher needs, but also on how to best deliver teacher training in order to acquire such knowledge and skills (Darling-Hammond et al., 2017). Hence, it is particularly important to evaluate the design and facilitation of teacher professional development (PD) courses to maximize learning and transfer of training. This action research study investigated the instructional approaches offered in a PD course in a FL institute and teachers' perceptions of benefits and drawbacks of each approach on their learning. A mixed method approach (Teddlie & Tashakkori, 2009; Tsushima, 2017) was followed to obtain a holistic understanding of the issue. Quantitative and qualitative data were collected. This included tracking the time spent on different instructional approaches over two iterations of the course in two different Middle-Eastern (ME) language schools and using a survey with open-ended questions to collect teachers' input about the instructional approaches. Four course facilitators and thirteen teachers participated in the study. Data analysis indicated that mentoring played a significant role in participants' learning. The mentoring sessions embedded within the workshop instructional hours and the one-on-one ad hoc out of class mentoring sessions, constituting 73% of the total instructional hours, were perceived as being instrumental to the participants' learning experiences. One implication for teacher trainers is that they need to be aware of what specific personal and professional qualities they bring to mentoring teachers or what skills they do not yet possess. Teacher training courses and on-going reflective practice need to include such opportunities.